Name

glCompressedTexImage2D — specify a two-dimensional compressed texture image

C Specification

void glCompressedTexImage2D(GLenum target,
 GLint level,
 GLenum internalformat,
 GLsizei width,
 GLsizei height,
 GLint border,
 GLsizei imageSize,
 const GLvoid * data);
 

Parameters

target

Specifies the target texture. Must be GL_TEXTURE_2D.

level

Specifies the level-of-detail number. For paletted formats, where all mipmap levels are loaded at once, this parameter is overloaded to represent the negative of the greatest mipmap level included in data.

internalformat

Specifies the color components in the texture. The following symbolic constants are accepted: GL_PALETTE4_RGB8_OES, GL_PALETTE4_RGBA8_OES, GL_PALETTE4_R5_G6_B5_OES, GL_PALETTE4_RGBA4_OES, GL_PALETTE4_RGB5_A1_OES, GL_PALETTE8_RGB8_OES, GL_PALETTE8_RGBA8_OES, GL_PALETTE8_R5_G6_B5_OES, GL_PALETTE8_RGBA4_OES, and GL_PALETTE8_RGB5_A1_OES.

width

Specifies the width of the texture image. Must be 2n for some integer n. All implementations support texture images that are at least 64 texels wide.

height

Specifies the height of the texture image. Must be 2m for some integer m. All implementations support texture images that are at least 64 texels high.

border

Specifies the width of the border. Must be 0.

imageSize

Specifies the size of the compressed image data in bytes.

data

Specifies a pointer to the compressed image data in memory.

Description

glCompressedTexImage2D defines a two-dimensional texture image or cube-map texture image using compressed image data from client memory. The texture image is decoded according to the definition of the internalformat. In addition to the paletted formats described below, OpenGL ES provides a mechanism to obtain symbolic constants for other formats provided by extensions. The number of compressed texture formats supported can be obtained by querying the value of GL_NUM_COMPRESSED_TEXTURE_FORMATS. The list of specific compressed texture formats supported can be obtained by querying the value of GL_COMPRESSED_TEXTURE_FORMATS.

The required compressed formats are paletted textures. The layout of the compressed image is a palette followed by multiple mip-levels of texture indices used for lookup into the palette. The palette format can be one of R5_G6_B5, RGBA4, RGB5_A1, RGB8, or RGBA8. The texture indices can have a resolution of 4 or 8 bits. As a result, the number of palette entries is either 16 or 256. If level is 0, only one mip-level of texture indices is described in data. Otherwise, the negative value of level specifies up to which mip-level the texture indices are described. A possibly remaining pad nibble for the lowest resolution mip-level is ignored.

Notes

glPixelStorei has no effect on compressed texture images.

glCompressedTexImage2D specifies the two-dimensional texture for the currently bound texture, specified with glBindTexture, and the current texture unit, specified with glActiveTexture.

Errors

GL_INVALID_ENUM is generated if target is not GL_TEXTURE_2D.

GL_INVALID_VALUE may be generated if if internalformat is not one of the paletted formats and level is greater than 0 or the absolute value of level is greater than log2max , where max is the returned value of GL_MAX_TEXTURE_SIZE.

GL_INVALID_VALUE may be generated if if internalformat is not one of the paletted formats and level is less than 0 or greater than log2max , where max is the returned value of GL_MAX_TEXTURE_SIZE.

GL_INVALID_ENUM is generated if internalformat is not one of the accepted symbolic constants.

GL_INVALID_VALUE is generated if width or height is less than 0 or greater than GL_MAX_TEXTURE_SIZE, or if either cannot be represented as 2k for some integer k.

GL_INVALID_VALUE is generated if border is not 0.

GL_INVALID_VALUE is generated if imageSize is not consistent with format, dimentions, and contents of the compressed image.

Associated Gets

glGet with arguments GL_NUM_COMPRESSED_TEXTURE_FORMATS and GL_COMPRESSED_TEXTURE_FORMATS

glGet with argument GL_MAX_TEXTURE_SIZE

See Also

glActiveTexture, glBindTexture, glCompressedTexSubImage2D, glCopyTexImage2D, glCopyTexSubImage2D, glPixelStorei, glTexEnv, glTexImage2D, glTexParameter

Copyright

Copyright © 2003-2004 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.